I am looking at using my Udoo Quad in a vehicle for several things (GPS/nav, APRS with ham radio, and general Android stuff), and powering it off the vehicle. From what I can tell, this should generally work, but I have two questions for someone who may have tried it... 1) Generally, will the Udoo need power regulation/filtering/conditioning? (yeah, I know this will generally depend on my vehicle.) Just curious what folks who had tried car projects had found. Basically, should I plan to add a 12V regulator between the car "12VDC" rail and the Udoo, or just hook it up? 2) Any idea what the current draw of an Udoo quad with a 7" panel attached will be? What's a good fuse to use? Thanks much in advance - Richard Perry
Udoo boards are not especially picky about input voltage, and don't require regulated +12V. I've operated them from batteries and solar power, over a voltage range of about 10-14.8V, including with a rather "noisy" engine-alternator (DC generator) charge source on one occasion. Nothing ties into the +12V directly (though it is passed through to the "V-in" pin on the Arduino headers, where some shields may use it)-- rather, this feeds a set of onboard DC-DC buck converters to yield regulated +5V, +3.3V, +2.5V and +1.2V. On an automotive electrical system, engine starting transients and "load dump" voltage spikes can be of particular concern. The Udoo does have a Zener clamping diode (SMAJ18CA) across the input jack that should clip high (or negative) voltage spikes of moderate energy level. I'd consider another, large diode like this across the incoming +12V, and maybe a passive LC (coil/choke + capacitor) filter as well, but you can probably get by with just the on-board protection. You might want something to delay power-on for a second or so during engine cranking, to avoid multiple on/off/on events and possible crashes from the interrupted boot cycle. As for current demand, I've never seen an Udoo pull more than 6W (0.5A @ 12V) at full load by itself, and would estimate a similar maximum draw for the small LCD. Even with a 2.5" hard drive, multiple USB devices, etc. also feeding from the udoo, a fuse of 3A should give plenty of headroom. If you can't find one that small, 5A should still be reasonably safe. btw, if you don't need the Wifi module, removing it will save 0.5 - 1W or so, and the header underneath can then serve as a 4th USB port.
I'm currently running my Udoo in my Jeep as a media infotainment system. I'm using software I've written called Autosense I've found that unless the engine is running I get random reboots rather quickly. I'm assuming it's voltage related, but have yet to dig deep into the voltage at the board when it happens. I've also just finished a hardware module that will clamp the power on once the accessory line goes high and using the GPIO pins send a power off signal. I've yet to finish the software yet. But if I can't get the system to stay running of batter for a decent amount of time the piece is useless.
Are there any other 12V loads running in your car while the engine's off? Large cooling fan? My first suspect for a random-reboot problem would be some sort of switching event causing a brief voltage dip. Do you have a multimeter with a "Min/Max" logging function? Connecting this, set to the fastest possible sampling rate (e.g. "Fast Min/Max" on Flukes) across the Udoo's power input might turn something up. Since all ground connections on Udoo are common with the power negative, possible ground-loop issues with a connected amplifier or other equipment could be playing a role too. A large electrolytic capacitor across the Udoo's supply input, ideally fed through a pair of large inductors (or, if you only have one handy, inline with the +12 wire) may help. Say, 10,000uF or more. You probably don't need to go too crazy with the ~1F Supercaps used in car audio, though one of those (plus series inductor) may be enough to solve the engine cranking problem too.
